Microbiome-Modulating Prophylaxis RCT: Antibiotic vs Gynoflor in Postmenopausal Women With Recurrent Cystitis

Who May Qualify: - Female, postmenopausal, age ≥40 years - Clinical history of recurrent urinary tract infection (rUTI) as assessed by the investigator - Able and willing to take assigned prophylaxis for 6 months - Able to attend baseline and Month 6 study visits and provide urine samples - Able to provide written willing to sign a consent form - Willing and able to complete twice-weekly phone/LINE follow-ups Who Should NOT Join This Trial: - Current symptomatic UTI at enrollment (may be treated and reconsidered after resolution) - Known hypersensitivity or contraindication to nitrofurantoin or to the Lactobacillus/estriol vaginal tablet (Gynoflor) or their excipients; significant renal impairment or other label-based contraindications to nitrofurantoin per local practice - Planned urologic surgery or procedure expected during the 6-month study period - Recent bacterial vaginosis (e.g., within the past month) or active vulvovaginal skin disorders precluding vaginal product use - History of hormone-dependent malignancy (e.g., breast, uterine, or cervical cancer) or unexplained abnormal vaginal bleeding - Significant liver disease (e.g., active hepatitis) or other conditions judged by the investigator to make participation unsafe - Participation in another interventional trial that could interfere with outcomes - Withdrawal of consent or severe adverse event requiring discontinuation Always talk to your doctor about whether this trial is right for you.